Joint structure of branch connector for common rail

Abstract

A joint structure of a branch connector for a common rail capable of securing axial force applied to a seal surface and a branch connector and increasing bending fatigue strength of the branch connector is provided. In the joint structure of the branch connector for the common rail which includes a screw sleeve concentric with a bearing surface of a main pipe rail and connects a branch connector to the main pipe rail via a sleeve washer which has been externally fixed to the branch connector in advance to be combined therewith as one piece, a clearance is provided between an inner surface of the sleeve washer at an external opening thereof and an outer surface of the branch connector.

1. A joint structure of a branch connector for a common rail, comprising a screw sleeve concentric with a bearing surface of a main pipe rail and connecting a branch connector to the main pipe rail via a sleeve washer which has been externally fixed to the branch connector in advance to be combined therewith as one piece, wherein:
 the branch connector has a main body with an outer surface, at least a portion of which is cylindrical; 
 the sleeve washer has a first end facing substantially towards the main pipe rail, a second end opposite the first end and an inner surface extending from the first end to the second end, the inner surface having a first longitudinal section in proximity to the first end of the sleeve washer, the first longitudinal section being cylindrical and being fixed rigidly to the outer surface of the main body of the branch connector; and 
 the inner surface having a second longitudinal section extending from the first longitudinal section of the inner surface of the sleeve washer to the second end of the sleeve washer, the second longitudinal section being spaced outwardly from the outer surface of the main body of the branch connector so that a clearance is provided between the inner surface of the sleeve washer and the outer surface of the branch connector along the second longitudinal section of the inner surface of the sleeve washer, wherein the clearance is provided by a taper surface formed by outwardly enlarging a diameter of the inner surface of the sleeve washer along the second longitudinal section. 
 
   
   
     2. The joint structure of a branch connector for a common rail as set forth in  claim 1 , wherein the tapered surface at the second end is an outwardly curved arc surface. 
   
   
     3. The joint structure of a branch connector for a common rail as set forth in  claim 2 , wherein the first and second longitudinal sections of the inner surface meet at the outwardly curved arc surface. 
   
   
     4. The joint structure of a branch connector for a common rail as set forth in  claim 1 , wherein the tapered surface is aligned to the first longitudinal section of the inner surface at an angle within a range from 4 to 15 degrees. 
   
   
     5. The joint structure of a branch connector for a common rail as set forth in  claim 1 , wherein a length of the clearance measured parallel to an axial center of the branch connector is set within a range from 0.5 D to 1.2 D when D is an outside diameter of the branch connector. 
   
   
     6. The joint structure of a branch connector for a common rail as set forth in  claim 1 , wherein the first longitudinal section defines an axial length that exceeds a radial thickness of the sleeve washer along the first longitudinal section. 
   
   
     7. The joint structure of a branch connector for a common rail as set forth in  claim 1 , wherein no part of the inner surface of the sleeve washer is threaded. 
   
   
     8. A joint structure for a common rail, comprising:
 a main pipe rail having a peripheral wall and a flow passage extending axially therethrough, a branch hole extending outwardly through the peripheral wall from the flow passage and an outwardly tapered bearing surface communicating with the branch hole; 
 a screw sleeve secured to the wall of the main pipe rail and being concentric with the bearing surface; 
 a branch connector having a connecting head at one end, a pressing bearing surface on the connecting head contacting the bearing surface of the main pipe rail, the branch connector having a main body adjacent the connecting head, the main body being formed with an outer surface, at least a portion of the outer surface of the main body adjacent the connecting head being cylindrical; and 
 a sleeve washer having opposite first and second ends and an inner surface extending between the ends of the sleeve washer, the inner surface of the sleeve washer being telescoped over the branch connector so that the first end thereof is substantially adjacent the connecting head of the branch connector, the inner surface of the sleeve washer having a substantially cylindrical first longitudinal section in proximity to the first end and a second longitudinal section extending from the first longitudinal section to the second end of the sleeve washer, the first longitudinal section of the inner surface of the sleeve washer being fixed rigidly to the cylindrical portion of the outer surface of the main body of the branch connector adjacent the connecting head, the outer surface of the branch connector and the second longitudinal section of the inner surface of the sleeve washer being configured so that a clearance is defined between the branch connector and the inner surface of the sleeve washer adjacent the second end thereof, wherein the clearance is provided by a taper formed by outwardly enlarging a diameter of the inner surface of the sleeve washer along the second longitudinal section of the inner surface. 
 
   
   
     9. The joint structure for a common rail as set forth in  claim 8 , wherein the taper includes an outwardly curved arc surface at the second end. 
   
   
     10. The joint structure for a common rail as set forth in  claim 8 , wherein the taper meets the substantially cylindrical first longitudinal section of the inner surface at an outwardly curved circular arc surface. 
   
   
     11. The joint structure for a common rail as set forth in  claim 8 , wherein the taper is aligned to the substantially cylindrical first longitudinal section of the inner surface at an angle in a range from 4 to 15 degrees. 
   
   
     12. The joint structure for a common rail as set forth in  claim 8 , wherein a length of the clearance in a direction of an axial center of the branch connector is set within a range from 0.5 D to 1.2 D when D is an outside diameter of the branch connector. 
   
   
     13. The joint structure of a branch connector for a common rail as set forth in  claim 8 , wherein the first longitudinal section defines an axial length that exceeds a radial thickness of the sleeve washer along the first longitudinal section. 
   
   
     14. The joint structure of a branch connector for a common rail as set forth in  claim 8 , wherein no part of the inner surface of the sleeve washer is threaded. 
   
   
     15. A joint structure of a branch connector for a common rail, comprising a screw sleeve concentric with a bearing surface of a main pipe rail and connecting a branch connector to the main pipe rail via a sleeve washer which has been externally fixed to the branch connector in advance to be combined therewith as one piece, wherein:
 the branch connector has a main body with an outer surface, at least a portion of which is cylindrical; 
 the sleeve washer has a first end facing substantially towards the main pipe rail, a second end opposite the first end and an inner surface extending from the first end to the second end, the inner surface having a first longitudinal section in proximity to the first end of the sleeve washer, the first longitudinal section being cylindrical and being fixed rigidly to the outer surface of the main body of the branch connector; and 
 the inner surface having a second longitudinal section extending from the first longitudinal section of the inner surface of the sleeve washer to the second end of the sleeve washer, the second longitudinal section being spaced outwardly from the outer surface of the main body of the branch connector so that a clearance is provided between the inner surface of the sleeve washer and the outer surface of the branch connector along the second longitudinal section of the inner surface of the sleeve washer, wherein the clearance is provided by a circular arc surface formed by outwardly enlarging a diameter of the inner surface of the sleeve washer at the second end. 
 
   
   
     16. A joint structure of a branch connector for a common rail comprising a screw sleeve concentric with a bearing surface of a main pipe rail and connecting a branch connector to the main pipe rail via a sleeve washer which has been externally fixed to the branch connector in advance to be combined therewith as one piece, wherein:
 the branch connector has a main body with an outer surface, at least a portion of which is cylindrical; 
 the sleeve washer has a first end facing substantially towards the main pipe rail, a second end opposite the first end and an inner surface extending from the first end to the second end, the inner surface having a first longitudinal section in proximity to the first end of the sleeve washer, the first longitudinal section being cylindrical and being fixed rigidly to the outer surface of the main body of the branch connector; and 
 the inner surface having a second longitudinal section extending from the first longitudinal section of the inner surface of the sleeve washer to the second end of the sleeve washer, the second longitudinal section being spaced outwardly from the outer surface of the main body of the branch connector so that a clearance is provided between the inner surface of the sleeve washer and the outer surface of the branch connector along the second longitudinal section of the inner surface of the sleeve washer, wherein the clearance is provided by a first circular arc surface on the inner surface of the sleeve washer at the second end and a second circular arc surface formed between the first circular arc surface and the first longitudinal section of the inner surface, the second circular arc surface being larger than the first circular arc surface. 
 
   
   
     17. A joint structure for a common rail, comprising:
 a main pipe rail having a peripheral wall and a flow passage extending axially therethrough, a branch hole extending outwardly through the peripheral wall from the flow passage and an outwardly tapered bearing surface communicating with the branch hole; 
 a screw sleeve secured to the wall of the main pipe rail and being concentric with the bearing surface; 
 a branch connector having a connecting head at one end, a pressing bearing surface on the connecting head contacting the bearing surface of the main pipe rail, the branch connector having a main body adjacent the connecting head, the main body being formed with an outer surface, at least a portion of the outer surface of the main body adjacent the connecting head being cylindrical; and 
 a sleeve washer having opposite first and second ends and an inner surface extending between the ends of the sleeve washer, the inner surface of the sleeve washer being telescoped over the branch connector so that the first end thereof is substantially adjacent the connecting head of the branch connector, the inner surface of the sleeve washer having a substantially cylindrical first longitudinal section in proximity to the first end and a second longitudinal section extending from the first longitudinal section to the second end of the sleeve washer, the first longitudinal section of the inner surface of the sleeve washer being fixed rigidly to the cylindrical portion of the outer surface of the main body of the branch connector adjacent the connecting head, the outer surface of the branch connector and the second longitudinal section of the inner surface of the sleeve washer being configured so that a clearance is defined between the branch connector and the inner surface of the sleeve washer adjacent the second end thereof, wherein the clearance is provided by a circular arc surface formed by outwardly enlarging a diameter of the inner surface of the sleeve washer at the second end. 
 
   
   
     18. A joint structure for a common rail, comprising:
 a main pipe rail having a peripheral wall and a flow passage extending axially therethrough, a branch hole extending outwardly through the peripheral wall from the flow passage and an outwardly tapered bearing surface communicating with the branch hole; 
 a screw sleeve secured to the wall of the main pipe rail and being concentric with the bearing surface; 
 a branch connector having a connecting head at one end, a pressing bearing surface on the connecting head contacting the bearing surface of the main pipe rail, the branch connector having a main body adjacent the connecting head, the main body being formed with an outer surface, at least a portion of the outer surface of the main body adjacent the connecting head being cylindrical; and 
 a sleeve washer having opposite first and second ends and an inner surface extending between the ends of the sleeve washer, the inner surface of the sleeve washer being telescoped over the branch connector so that the first end thereof is substantially adjacent the connecting head of the branch connector, the inner surface of the sleeve washer having a substantially cylindrical first longitudinal section in proximity to the first end and a second longitudinal section extending from the first longitudinal section to the second end of the sleeve washer, the first longitudinal section of the inner surface of the sleeve washer being fixed rigidly to the cylindrical portion of the outer surface of the main body of the branch connector adjacent the connecting head, the outer surface of the branch connector and the second longitudinal section of the inner surface of the sleeve washer being configured so that a clearance is defined between the branch connector and the inner surface of the sleeve washer adjacent the second end thereof, wherein the clearance is provided by a first circular arc surface on the inner surface of the sleeve washer at the second end and a second circular arc surface formed between the first circular arc surface and the first longitudinal section of the inner surface, the second circular arc surface being larger than the first circular arc surface.